For example, as shown in FIG. 11, in a continuously variable transmission (CVT) 200, a continuously variable transmission belt 100 including a plurality of stacked metal elements 101 which are supported by an endless ring 102 is wound around a drive sheave KS and a driven sheave JS. The drive sheave KS and the driven sheave JS are each provided with a fixed sheave and a movable shave of conical plate-like shapes. The CVT 200 is configured to steplessly change gears from high speed to low speed in such a way that each movable sheave moves in directions of shafts J1 and J2 to change a radius of gyration of the wound CVT belt 100.
In general, when the CVT belt 100 travels from the drive sheave KS to the driven sheave JS (in a direction indicated with an arrow FF), no gaps are present in between the metal elements 101, but when the belt 100 travels from the driven sheave JS to the drive sheave KS (in a direction indicated with an arrow FB), slight gaps (for example, about 0.5 to 0.8 mm in total) are generated in between the metal elements 101. These gaps cause slips between the metal elements 101 and the drive sheave KS in a region KD where the CVT belt 100 is wound around the drive sheave KS, lowering efficiency in transmitting a driving force.
In order to prevent the above problem, the present applicant has disclosed a technique of blowing air against the CVT belt 100 in its traveling direction to fill the gaps between the metal elements 101 in a stacking direction during the CVT belt 100 travels from the driven sheave JS to the drive sheave KS (see Patent Document 1).